The polyphenylene ethers and processes for their preparation are known in the art and described in numerous publications including Hay, U.S. Pat. Nos. 3,306,874 and 3,306,875. Other procedures are described in Van Dort, U.S. Pat. No. 3,365,422, Bennett and Cooper, U.S. Pat. Nos. 3,639,656, 3,642,699, 3,733,299, 3,838,102 and 3,661,848. All of these patents are incorporated by reference.
The processes most generally used to produce the polyphenylene ethers involve the self-condensation of a monovalent phenol in the presence of an oxygen-containing gas and a catalyst. Thereafter, chelating agents have been used to extract the catalyst into an aqueous phase which can be separated from the polymer solution or simply to form a chelate with the catalyst which is soluble in the precipitating medium (if the phases are not separated before precipitation). Antisolvents have been used to cause the polyphenylene ether polymer to precipitate.
Various additives for the promotion of the self-condensation of the monovalent phenol have been disclosed which include quaternary ammonium compounds, inorganic bromides, phosphonium compounds and sulfonium compounds. While the prior art promoters have been satisfactory as reaction promoters, it has been noted that problems are still encountered in the subsequent polymer recovery procedures and in the procedures that are used to separate the reaction solvent from the antisolvent for recycling purposes.
It has now been found that a distinct class of polyethoxylated quaternary ammonium salts may be employed to promote polyphenylene ether polymerizations, to enhance the removal of catalyst residues and to increase the phase separation of reaction solvent and antisolvent by preventing the emulsification of the antisolvent and solvent.
Accordingly, it is a primary object of this invention to provide a promoted process for the preparation of a polyphenylene ether which contributes to the overall efficiency of the process, including the solvent recovery operations.
It is also an object of this invention to provide a novel promoted polyphenylene polymerization method.
It is also an object of this invention to provide a novel means of reducing the amount of copper catalyst residue in polyphenylene ether polymers.
It is also an object of this invention to provide a means of increasing the phase separation rate of polyphenylene ether reaction solvent and the antisolvent that is employed for the separation of a polyphenylene ether from its reaction mixture.